MRI Simulation-guided Boost in Short-course Preoperative Radiotherapy for Unresectable Rectal Cancer

Short-course preoperative radiotherapy(SCPRT), which consists of 5 Gy x 5f and 4Gy for boost on the GTV with MRI-simulation alone.

Long-term chemoradiotherapy(CRT), which consists of a long-term chemoradiation (2 Gy x 25 with capecitabine) preoperatively.

Patients will receive consolidation chemotherapy after 7-10 days of SCPRT completed, given in 3 week cycle of capecitabine 1000 mg/m2 twice daily, day 1-14 combined with oxaliplatin 130 mg/m2 once. In total, 4 cycles of neoadjuvant chemotherapy are scheduled before surgery.